An NSF post on Twitter this morning described an interesting study from the University of Pennsylanvia and Cornell University, that found that some people who call themselves “African Americans” may only be 1% West African, according to their DNA.

The University of Pennsylvania press release contains other interesting findings as well. 365 individuals were studied and 300,000 genetic markers were examined.

Some of the findings were:

If you’re African American, the genes most likely to have an African origin are those on your X chromosome. The article didn’t mention it, but I would guess that also be true of your mitochondrial genes since X chromosomes and mitochondria are inherited from your mother.

The median amount of European DNA in African Americans was 18.5 percent.

The researchers were able to distinguish between genes that came from different parts of West Africa. This finding will probably help improve the accuracy of personal ancestry tests and give people better information about the homes of their ancestors.

One bit of frustration, though. I tried to find the original article and the most recent paper in PubMed was from May. I wish press releases would include links to these. Even the title of the paper would be nice.

I got this from clicking your UPenn link and then clicking on Tishkoff, since she’s one of the researchers. The Tishkoff lab site has links to publications. I’m no expert on these things. Does “”in press” mean “not published yet”?

Yes. Specifically, it means that the corresponding author has the acceptance letter from the editor in hand but the print version is not yet available. In the case of Science, it may have been published online–they have been known to post articles on their web site several weeks before the print version appears.

The 2009 paper you mention doesn’t include Bustamante, who is specifically noted to be a coauthor in the press release (so I included him in the Google terms, and found the paper pretty quickly), and the publication date makes more sense. It’s available — probably just available, hence the press rlease timing — as an Open Access paper in PNAS’s Early Edition ( doi: 10.1073/pnas.0909559107 )

It is a huge pain when the press release doesn’t cite the paper and I really don’t understand why they don’t.